Blow-off cock



No. 620,287. Patented Feb. 28, |899.

n. s. DUNNELLY.

. BLUW-OFF 600K.

(Application led Oct. 18, 1898.)

(No Modem y y I %illllle 1727.1. al Y UNITED STATES PATENT OFFICE.

DANIEL B. DONNELLY, OF PITTSBURG, PENNSYLVANIA.

BLOW-OFF COCK.

SPECIFICATION forming part of Letters Patent No. 620,287, dated February 28, 1899.

Application iiled October 18, 1898. Serial No. 693,848. (No model.)

To all whom it may concern,.-

Be it known that I, DANIEL B. DONNELLY, a citizen of the United States,residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Blow-Off Cocks; and I do declare the following to be a full, clear, and exact description kof the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters of reference marked thereon,which form a part of this specification.

My invention relates to blow-off cocks for steam-boilers, and is an improvement upon the blow-off cock patented to me December 17, 1895, No. 551,370.

The object of the present invention is to provide means for both closing and opening the valve by hand without interfering with its free actuation by the duid-pressure, and, further, to provide an auxiliary valve for closing the discharge-opening in case of accident to or clogging of the main valve.

In the accompanying drawings, Figure 1 is a longitudinal section of a blow-oft cock embodying myimprovements. Fig. 2 is a modification of one part, and Fig. 3 shows a detail of construction.

The casing A has at its upper end a screwthreaded neck c, for attaching it to the shell ofthe boiler. At the outer and inner ends of the neck are valve-seats preferably formed ou the ends of.a removable bushing A', which has a flange a abutting solidly on the end of the neck a. The valve-seats a2 a3 are at each end of the bushing, the inner end of which projects into the casing, as shown.

The main valve B has wings b to guide it in the bushing. It seats upon the outer seat co2 and has a bridge b on its under side,through which passes the reduced end of the valvestem C. A nut D in the space between the bridge and the valve engages the threaded end of the stem, whereby the valve is rotatably secured to the stem.

An auxiliary valve C is'formed upon or attached to the stem C, adapted to seat against the inner seat as on the bushing. Below the auxiliary valve the stem is tubular to fit the polygonal spindle D. The spindle is preferably square along that portion which enters the valve-stem; but it is round where it passes through the cap A2 of the casing, so as to be rotatable therein.

The Valve-stem is longitudinally movable in the tubular piston-rod E of the piston E. Preferably the lower end of the stem is slightly enlarged and is screw-threaded externally to mesh into screw-threads forlned on the inside of the tubular piston-rod, which rises centrally from the piston through the depending neck 0,5 on the septum a4, which divides the casing into two chambers. The lower end of the neck d5 is formed to makefa tight joint upon an annular face provided on a shoulder on the rod E' near its junction with the piston. The upper end of the tubular piston-rod is finished off to fit snugly against the back of the auxiliary valve C', preferably entering a groove c formed therein.

The piston E is fitted to reciprocate in the cylindrical lower chamber of the casing and may have packing e in peripheral grooves. A helical spring F is confined between the piston and the septum. The piston is provided with wings e', which interlock with wings a6 on the depending neck a5 to prevent the piston from rotating.

The spindle D has a collar d received in a recess in the cap A2 and confined bya union A3, which compresses packing G against the lower face of the collar. This construction `permits the spindle to be turned without any axial movement. A modied arrangement is shown in Fig. 2, where the packing is replaced by a spring H, which-keeps the ground face of the collar d closelypressed to its seat in the cap A2.

One or more lugs a7 are provided just inside the opening a8 of the casing to prevent the escape-pipe from being screwed too far into the casing. A vent a9 allows the escape of steam or air leaking into the lower chamber above the piston.

The opening al is connected with a supply of compressed air or the like, and when the valve B is to be opened fluid-pressure is admitted below the piston, lifting it to the position shown in Fig. 1 and opening the valve, the stem C sliding freely on the spindle D. If for any cause the main valve refuses to seat after the pressure has been removed from under the piston, the auxiliary valve can be closed by turning the hand-wheel D on the spindle. This operation will rotate the valvestem inside of the piston-rod, causing the former to advance along the threads until the auxiliary valve is forced against the seat a3, closing the boiler-outlet. This operation forces the main valve still farther open, allowing anything that may be under the valve to escape. When the main valve is seated,it can be opened by hand by turning the handwheel. It will thus be seen that both valves are under control of the hand-Wheel and that the main valve is free to be opened and closed by the piston and the spring independently of the hand operating devices.

Having thus described my invention, what I claim isl. A blow-off cock having a main valve opening inwardly against the boiler-pressure, means for opening said valve by fluid-pressure, and a hand operating device adapted to cause a relative movement between the valve and the Iiuid pressure operating devices, whereby said valve can be opened and closed by hand independently of and without actuating t-he luidpressure -operating devices, substantially as described.

2. A blow-oft cock, having a main valve arranged to be operated by fluid-pressure, an auxiliary valve on the same stem, and means for operating both valves by hand independentlyot' the fluid-pressure-actuating devices, substantially as described.

3. A blow-off cock,havin g a main valve and an auxiliary valve both on the same stem, a seat for each valve on a portion of the casing lying between said valves, and means for opening and closing said valves alternately, substantially as described.

4. A blow-off cock, having a main valve, a piston having a tubular rod, avalve-stem attached to the main valve and adjustable in said tubular piston-rod, and means for adjusting said stem by hand, substantially as described.

5. A blow-OEE cock, having a main valve, a piston having a tubular rod, a valve-stem screwing into said rod, and means for rotating said stem by hand, substantially as described.

6. A blow-ott cock, having a main valve, a piston having a tubular rod, a valve-stem screwing into said rod, and having a polygonal socket, and a polygonal spindle entering said socket, substantially as described.

7. In a blow-olf cock, the combination with a piston having a tubular rod, of a valvestem movable lengthwise therein, and coperating faces on the end of the rod and on the stem, substantially as described.

S. In a blow-off cock, the combination with a main valve, of a piston for operating it by Huid-pressure, a rotatable spindle for operating it by hand, and means for preventing the piston from rotating, substantially as described.

9. In a blow-off cock, the combination with the piston E having wings e', of the casingA provided with interlocking wings a, substantially as described.

lO. In a blow-off cock,the combination with a removable bushing, having a valve-seat on each end, of a main valve and an auxiliary valve mounted on the same stem, and so arranged that when one is seated the other will be open, substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

DANIEL B. DONNELLY.

Witnesses:

S. A. DIXON, W. H. STERRITT. 

